Method to recycle plastics, electronics, munitions or propellants using a metal reactant alloy composition

ABSTRACT

This invention relates to a method and apparatus for recycling plastics, electronics, munitions or propellants. In particular, the method comprises reacting a feed stock with a molten aluminum or aluminum alloy bath. The apparatus includes a reaction vessel for carrying out the reaction, as well as other equipment necessary for capturing and removing the reaction products. Further, the process can be used to cogenerate electricity using the excess heat generated by the process.

PRIORITY

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/162,648, filed on May 15, 2015, which is incorporated byreference in its entirety herein.

FIELD OF THE INVENTION

The present invention relates to a method to recycle plastics,electronics, munitions or propellants and to capture and recover carbon,sulfur, hydrocarbons, and heavy metals from the plastics, electronics,munitions or propellants using a molten aluminum or aluminum alloy baththat may be composed of aluminum, zinc, iron, copper, silicon, and/orcalcium alloys.

BACKGROUND OF THE INVENTION

Although a number of methods exist to recycle plastics, electronics,munitions or propellants, these methods are costly and in some casescreate a secondary waste that can be more of a problem than the actualinitial material itself. Currently, methods of recycling plastics,electronics, munitions or propellants create greenhouse gases such ascarbon monoxide or carbon dioxide, as well as, other byproducts such asammonia and other secondary compounds, which in some cases are morehazardous than the parent material. Further, these processes alsoproduce slag, which currently must be land filled and there is currentlyno efficient method to recovery heavy metals, such as mercury, or rareearth metals that typically are found in electronics. While theseprocesses work, they require significant energy input or create wastestreams that must be disposed of at a cost to the operator and withpotential future environmental impact.

Thus, there is a need in the art for an improved method to economicallyrecycle plastics, electronics, munitions or propellants while recoveringthe remaining carbon, sulfur and any rare earth or heavy metals.

SUMMARY OF THE INVENTION

The present invention provides an apparatus for recycling plastics,electronics, munitions or propellants. This can be any type of plastic,such as but not limited to PVC, HDPE, PF, LDPE, ABS, Nylon or otherplastics. This can be any consumer electronics such as but not limitedto Cell Phones, Portable Electronics Devices, Laptop Computers, Desk TopComputers, Tablets, etc. As well, this can be used to recycle any typeof munition or propellant such as, but not limited to, gun power or M6.The process utilizes a molten aluminum or molten aluminum alloy bath.The aluminum can be alloyed with metals that include, but are notlimited to zinc, iron, copper, silicon, and calcium. In all cases thematerial is ground and can be dried, and is then introduced into thebath below the surface. The ground material can be forced below thesurface using an inert gas such as nitrogen or argon or fed into thebath using a gravity feed. In the process excess heat is generated andcan be used to facilitate other processes such as cogeneration of power.As the ground material is passed through the bath, the aluminum oraluminum alloy bath reacts to break it down to its elemental parts.These elements are then removed from the bath using a gravimetricprocess and a gas capture process. The elements removed from the bathcan include, but are not limited to, carbon, sulfur, hydrogen, nitrogen,mercury, copper, iron, as well as other rare earth and heavy metals. Theprocess can also produce methane and other hydrocarbons. The elementalmaterials can be recovered and sold and the hydrocarbons are recoveredand sold or burned to facilitate the process. The inert gas isreprocessed and reused.

The aluminum or aluminum alloy bath is able to remove oxygen compoundsby chemically reacting with them at high temperature. Other compoundssuch as PVC are broken down as the aluminum or other alloys remove theChloride to form Aluminum Chloride. The removal of select elementsallows the bonds of the organic compounds to be broken, producingvolatile organic compounds, as well as elemental compounds.

This process has been evaluated in laboratory tests using selectplastics and consumer electronics. The ground plastics and consumerelectronics was passed through molten aluminum. The flue gas producedand the final alloy mass was analyzed using scanning electron microscope(SEM). The review of the SEM images showed the presence of elementcarbon, sulfur and aluminum salts. The only items that did not breakdown were the S-Glass, the silicon, and silica glass.

FIG. 1 shows the basic process flow 100. In the basic process, groundmaterial is introduced below the surface of the molten metal bath 103using an injection feed system 101 through feed line 102. The elementalmaterial, such as carbon, sulfur and the like, is captured 104, lessdense secondary compounds are removed from the surface of bath 105, anddenser secondary compounds are removed from the bottom of the bath 106.While this has been described as a method to recycle plastics,electronics, munitions or propellants, use of this method to recycleother organic compounds, such as, but not limited to rubbers, oils andtars are also contemplated.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference isnow made to the following descriptions taken in conjunction with theaccompanying Figures and drawings, in which:

FIG. 1 shows the basic process flow;

FIG. 2 shows a typical process flow;

FIG. 3 shows a detailed cross sectional view of the reaction vesselwall; and

FIG. 4 shows a modified flow process incorporating a vortex.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a process to recycle plastics,electronics, munitions or propellants. The process utilizes a moltenaluminum or molten aluminum alloy bath. The process utilizes a moltenaluminum bath as the reactant. The ground feedstock is introduced belowthe surface of the molten aluminum bath, reacts with the aluminum todecompose the feed stock. In the process, elemental carbon, sulfur,copper, iron, and rare earth and heavy metals and molecular hydrogen,nitrogen, methane, and other hydrocarbons are removed from the moltenbath. The products can be sold and the nitrogen is either vented to theatmosphere or captured.

The process utilizes a molten metal as the primary reactant. In thepreferred embodiments the molten metal is aluminum or an aluminum bath.The aluminum can also be alloyed with other elements including, but notlimited to, zinc, iron, copper, silicon and calcium. Other metals andmetal alloys such as calcium and silicon are also envisioned. The fluegas stream, which contains oxygen containing greenhouse gases producedby combustion processes, is passed through the aluminum alloy bath toremove the oxygen-containing gases from the flue gas stream.

In the process, excess heat is generated and can be used to facilitateother processes such as cogeneration of power. The excess generated bythe process is a function of the makeup of the greenhouse gases in theflue gas feed.

When the feed stock contains other compounds, those compounds can alsodecomposed or captured. For example, if the feed stock containsinorganic compounds, such as chlorine, the process will produce analuminum salt, in this case aluminum chloride. The present inventionalso provides a method and apparatus for capturing heavy metals, suchas, but not limited to mercury or rare earth metals, which are oftenfound in consumer electronics or munitions. In the process, the moltenmetal bath breaks down the metal compounds as they are introduced intothe molten metal bath. As additional aluminum is added to the bath, theheavy metals settle to the bottom of the reaction vessels and areremoved from the reaction vessel. While some aluminum may be entrainedin the heavy metals that are removed from the bottom of the reactionvessel, the aluminum can be removed and refined and the heavy metals canbe captured.

A detailed process flow 200 is shown in FIG. 2. While the processdescribed discusses processing recycling plastics, electronics,munitions or propellants can be processed using the invention. Theground feed stock is introduced into the treatment process throughblower feed line 211. Blower 210, which may be another type of injector,is used to inject the ground feed stock into reaction vessel 220 throughinjection line 212. Injection line 212 introduces the ground feed stock,which is entrained in an inert gas such as nitrogen, below the surfaceof the molten aluminum compound 226. Injection line 212 must besufficiently below the surface of the molten aluminum compound 226 toallow for sufficient mixing. The heavy products of the reaction,typically the heavy metals described above will settle out in thereaction vessel. The reaction vessel typically has a sloped bottom,however other designs such conical bottoms and the like can be utilized.Once the heavy products settle out, they are collected using collectionlines 223, 224, and 225. Collection lines 223, 224, and 225 allow forheavy metals of different densities to be removed. Depending on the sizeof the process, the heavy products can be continuously removed or abatch removal process can be used.

Reaction vessel 220 also includes an aluminum feed line 221, which isused to supply additional aluminum compound to replace that consumed bythe reaction with the ground feed stock. Additional heat may be requiredduring start-up, for example. Heater 227 is provided for this purpose.Heater 227 can be any type heater, including radiative, inductive, andconvective. For example, heater 227 would be a microwave heater or aradio frequency heater wherein the frequency is tuned for the metalalloy used.

Thus, the heat generated by the process must be removed. Section A,which is shown in more detail in FIG. 3 shows one way the heat can beremoved from the process. The reaction vessel 220 is lined with arefractory material 310, which protects the vessel wall 320. Coolingplate 330 is attached to the vessel wall 320 and cooling water iscirculated in the channels created between the cooling plant 330 and thevessel wall 320. Insulation 340 surrounds the cooling plate to maximizeheat recovery, as well as for safety purposes. Once the cooling waterpicks up the heat generated from the process, it can be either sent to acooling tower or the heat can be recovered and used for other purposes.If the process is used in a facility that needs a hot water source, thenthe heat recovery system can be designed for this purpose. However, theheat can also be used to generate electricity.

Turning back to FIG. 2, a steam turbine electric generation process isrepresented. In this case, the cooling water is introduced thoroughcooling feed 228. As the cooling water travels around the reactionvessel 220, it picks up heat and steam is generated. The steam generatedis then sent via steam line 229 to steam turbine 232. The steam passesthrough the turbine and as it condenses, turns the turbine blades ofturbine 232. Turbine 232 is coupled to generator 231. As the turbineturns the rotor of generator 231 though the stator, it generateselectricity. While this process is only briefly described, this steamturbine-electric generator process is well known in the art. And anysteam turbine-electric generator process could be utilized.

Also, as described above, the reaction will also produce elementalcarbon, elemental sulfur, molecular nitrogen and molecular hydrogen.These will be removed from the reaction vessel using blower 250. Blower250 will pull high temperature elemental carbon, elemental sulfur,molecular nitrogen and molecular hydrogen from the reaction vessel 220through heat exchanger feed line 241 into heat exchanger 240. Heatexchanger 240 will then cool this material to enable further processing.Any hydrocarbons that are produced may also be condensed in heatexchanger 240. These liquid hydrocarbons can be collected for furtheruse or sale. Heat exchanger 240 can be any heat exchanger, however inthe preferred embodiment, heat exchanger 240 is a forced air heatexchanger, however other heat exchangers, are also envisioned. Theprocess stream then leaves the heat exchanger through line 242 andpasses through blower 250 and blower discharge line 252 into two cycloneseparators. The first separator 260 separates out carbon from processstream. The carbon is collected though separation line 263. Theremaining process stream proceeds to the second separator 270, whichseparates out sulfur from the process stream. The sulfur may be removedusing a cold finger as the stream is cooled to less than 444 degreesCelsius. The sulfur is collected through separation line 273. Theremaining process stream, which may include gaseous nitrogen andhydrogen, is then separated in cryo unit 280. In this unit, the gasstream is cooled further and to allow the components to be separated.

Below is a list of possible ground feed stock that may be recycled, andthe resulting elemental outputs produced by the reactions within themolten metal bath.

-   -   Poly Vinyl Chloride: 2(C₂H₃Cl)_(n)→4C+3H₂+2Cl    -   Polypropylene: (C₃H₆)_(n)→3C+3H₂    -   PET: (C₁₀H₈O₄)_(n)→10C+4H₂+2O₂    -   Polycarbonate: (C₁₆H₁₄O₃)_(n)→16C+7H₂+30O₂    -   ABS: (C₈H₈*C₄H₆*C₃H₃N)_(n)→15C+17/2H₂+1N    -   4-(tert-butyl)styrene (butyl styrene):        -   (CH₃)₃C₆H₄CH═CH₂→12C+8H₂    -   Nylon 66: (C₁₂H₂₂N₂O₂)_(n)→12C+11H₂+2N+2O₂    -   Dibutyl Phthalate: 3C₁₆H₂₂O₄+8Al=48C+33H₂+4Al₂O₃    -   Diphenylamine: 2C₁₂H₁₁N+0Al=24C+22H₂+N₂    -   Nitrocellulose:        -   6C₆H₉(NO₂)O₅+12Al=36C+27H₂+3N₂+6Al₂O₃        -   2C₆H₉(NO₂)₂O₅+12Al=12C+9H₂+N₂+6Al₂O₃        -   6C₆H₉(NO₂)₃O₅44Al=36C+27H₂+9N₂+22Al₂O₃    -   Dinitrotoluene: 3C₇H₆N₂O₄+8Al=21C+9H₂+3N₂+4Al₂O₃

FIG. 4 illustrates a modified process flow 400 using a vortex entry. Aswith the process described in FIG. 2, the modified process enablesrecycling of plastics, electronics, munitions or propellants. Instead ofbeing directly injected into the aluminum bath, the ground feed stock isintroduced into the treatment process through line fed by a vortex 402.The vortex 402 is formed within a ceramic bowl 415 by pumping in moltenaluminum or aluminum alloy. The molten aluminum or aluminum alloy may beadded through a new aluminum input line 404, or it may be recirculatedfrom the aluminum bath using a pump 406. The ground feed stock (whichmay include any of the materials above that need to be recycled) maythen be introduced into the ceramic bowl 415 through a gravity feed 405.The ground feed stock mixes with the molten aluminum or aluminum alloyand the mixture is pulled to the bottom of the bowl from the rotation ofthe vortex 402. The bottom of the ceramic bowl 415 may have a connectingline 408 to the aluminum bath, and the mixture of ground feed stock andmolten aluminum or aluminum alloy enters the aluminum bath from theconnecting line 408. Other aspects of the modified process flow 400 aresimilar to that shown with the flow in FIG. 2.

The vortex entry illustrated in FIG. 4 allows for some benefits overother injection systems. The vortex allows better mixing of the groundfeed stock with the molten aluminum or aluminum alloy, which allows therecycling reactions to occur more efficiently. Additionally, because theground feed stock has already mixed with the molten aluminum in theceramic bowl 415, the temperature of the mixture has an opportunity toequalize, and the temperature may be relatively close to the temperatureof the molten aluminum within the bath. Accordingly, there is lesslocalized cooling, and a more consistent temperature gradient, at theentry injection point when the vortex entry is used.

As described above, once the feed stock enters the aluminum bath or thevortex, then reactions of the ground feed stock material with thealuminum or aluminum alloy bath will begin. The denser materials willbegin to settle while the lighter materials will rise. The lightestmaterials, such as gas will bubble to the surface, to be recoveredthere.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thedisclosure of the present invention, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present invention.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

What is claimed is:
 1. A method of recycling plastics, electronics,munitions or propellants, the method comprising: mixing a feed stockwith molten aluminum; injecting the molten aluminum and feed stockmixture into a reaction vessel containing further molten aluminum,wherein the injection occurs below the surface of the molten aluminum inthe reaction vessel; and reacting the feed stock with the moltenaluminum, such that oxygen and oxygen containing compounds in the feedstock are removed and aluminum oxides are formed.
 2. The method of claim1, wherein the molten aluminum comprises an aluminum alloy selected fromthe group consisting of silicon, magnesium, zinc, copper, iron, andcalcium.
 3. The method of claim 1, wherein mixing the feed stock withmolten aluminum comprises injecting, using a vortex of molten aluminumin a mixing vessel external to the reaction vessel, the feed stock intomolten aluminum.
 4. The method of claim 1 wherein the injection of themolten aluminum and feed stock mixture is sufficiently below the surfaceof the molten aluminum to allow for sufficient mixing.
 5. A method ofrecycling plastics, electronics, munitions or propellants, the methodcomprising: feeding molten aluminum into a bowl such that a vortex ofmolten aluminum is created in the bowl; feeding a feed stock into themolten aluminum in the bowl to create a molten aluminum and feed stockmixture; feeding the molten aluminum and feed stock mixture into areaction vessel containing further molten aluminum, wherein the moltenaluminum and feed stock mixture enter the reaction vessel below thesurface of the molten aluminum in the reaction vessel; allowing the feedstock to react with the molten aluminum in the reaction vessel; andcollecting heavy products produced in the reaction from collection linesin the reaction vessel; collecting less dense compounds from the surfaceof the molten aluminum in the reaction vessel using a blower and a heatexchanger.
 6. The method of claim 5, wherein the molten aluminumcomprises an aluminum alloy selected from the group consisting ofsilicon, magnesium, zinc, copper, iron, and calcium.